1. The Field of the Invention
The present invention is related to a novel sailboat and hull configuration which is particularly adaptable for use in sailboats such as catamarans. More particularly, the present invention is related to a catamaran which is collapsible and easily transportable together with a hull which includes twin hydrofoil structures.
2. Background of the Invention
While sailboating is, of course, an ancient activity dating back to approximately the beginning of recorded history, it has recently enjoyed a surge in popularity as a sport or leisure time activity. Sailboats of all descriptions are now in used in recreation. These include sailing yachts of 50 feet in length of more, as well as dinghys which may be well under 10 feet in length. One of the factors contributing to the popularity of sailboating as a sport is the wide variety of boats available. There are boats available to match virtually every type of taste.
Many types of basic sailboats are now on the market. One type of basic monohull recreational sailboat, which can be used for purposes of illustration, is approximately 14 feet long. This boat has generally vertical planar sides approximately 11/2 to 2 feet in height with a generally V-shaped hull. It has a 6 foot 2 inch beam, weighs about 265 pounds and is usually transported using a small trailer. This particular boat is equipped with a 75 square foot main sail and a 35 square foot jib. Thus, the total sail area is 110 square feet, which is typical in boats of this type. The boat employs a conventional daggerboard for stability and also to avoid slippage in the water as the wind catches the sail. The boat is also equipped with a conventional rudder mounted to the rear of the boat to facilitate steering and maneuvering the boat.
Many variations of such a basic recreational sailboat are currently on the market. Typically, however, basic boats of this type, which are approximately 14 feet in length, weigh between 250 and 350 pounds and have between 90 and 115 square feet of sail. These boats are easy to sail, but are not particularly fast. In addition, they are generally transported and stored using a conventional boat trailer.
In the late 1960's there was a desire by recreational sailboaters to develop a boat which would be more challenging and exciting to sail than the basic recreational sailboat described above. One concept was to take the general catamaran, or multiple hull, design which had been used on larger boats and employ it in smaller recreational boats. It was anticipated that the use of the multi-hull catamaran design would lead to a faster boat which was more exciting to sail.
One of the first makers of small recreational catamarans was Hobie Cat Corporation of Oceanside, California (now a subsidiary of Coleman Co.). That company began manufacturing small catamarans in 1968. This type of boat has received wide acceptance within the recreational boat market.
An analysis of the specifications of some small catamarans provides an understanding of their popularity and wide acceptance. While small catamarans may be 19 feet long and longer, for purposes of comparison with the basic boat described above, 14 foot catamarans are emphasized.
While the basic 14 foot sailboat weighs between 250 and 350 pounds, a 14 foot catamaran is typically about 50 pounds lighter weighing from about 195 to 300 pounds fully rigged. At the same time, recreational catamarans generally employ a much larger total sail area. While the basic boats described above have about 90 to 115 square feet of sail, a 14 foot catamaran generally has 120 to 150 square feet of sail, with several of the most popular 14 foot catamarans having sail areas in excess of 145 square feet. When comparing sail area to weight it can be seen that a typical basic boat may have a sail area to weight ratio of about 0.4 square feet/pound, while a typical catamaran of the same length may be expected to have a ratio approaching 0.8 square feet/pound. Thus, it can be appreciated that small recreational catamarans are generally must faster than their conventional counterparts, having about twice as much sail area per pound of boat.
An additional factor in the performance of sailboats is, of course, the hull configuration. Conventional sailboats have hulls which contact the water over an area approximately equal to the surface area of the boat (i.e. the average beam width times the length). Catamarans, conversely, have two or more hulls which contact the water over a relatively small area equal to only a small fraction of the surface area of the boat. FIG. 1 illustrates a typical recreational catamaran configuration 10. The two hull members 12 support the entire weight of the boat. Thus, while at rest the water line may be expected to be at a point approximately one-third to one-half of the distance up the hull, resulting in a small area of contact between the hull and the water. This reduced area of hull-water contact reduces the boat's resistance as it moves through the water, greatly increasing its potential speed of travel. This is particularly true when it is appreciated that in moderate to heavy winds, one of the boat's hull members 12 is likely to be lifted completely out of the water.
A major problem which has developed, however, is in maintaining the boat's stability while at the same time minimizing the wetted surface of the hulls. Essentially, two general types of hull configurations have been developed in the art. These hull types are the symmetrical hull and the asymmetrical hull. Cross sections of symmetrical and asymmetrical hulls are shown in FIGS. 2a-2d.
FIGS. 2a and 2b illustrate a popular configuration of an asymmetrical hull generally designated 14. When fully assembled the curved surface 16 of hull 14 would face the interior of the boat. FIG. 2a illustrates hull 14 at rest in the water. FIG. 2b illustrates the hull 14 as it would appear while traveling through the water at a point where the boat's other hull has lifted out of the water or is about to lift out of the water.
FIGS. 2c and 2d, conversely, illustrate a symmetrical hull design. The symmetrical hull is generally designated 18. FIG. 2c shows the symmetrical hull 18 at rest, while FIG. 2d shows the hull 18 as it would appear while traveling through the water. The characteristic common to symmetrical hulls is that the configuration of the inside surface 20 is essentially a mirror image of outside surface 22.
The major difference in operation between the symmetrical hull 14 and the asymmetrical hull 18 is the amount of wetted surface. Because of their shape, asymmetrical hulls, such as hull 14, have more wetted surface than do symmetrical hulls, such as hull 18. Thus, if this isolated factor were considered it would be expected that boats with symmetrical hulls 18 would be faster than boats with asymmetrical hulls 14.
A problem that arises in the use of symmetrical hulls, however, is that of stability. While the decreased wetted surface may make the hull faster, it also makes the hull less stable. It is often found, therefore, that in order to provide sufficient stability for a boat with symmetrical hulls, it is necessary to add daggerboards.
FIG. 3 is a side elevational view of one popular configuration of a small catamaran having symmetrical hulls. Shown in FIG. 3 are a hull 24, a rudder 26 and a daggerboard 28. It will be appreciated that the addition of a daggerboard 28 presents additional problems. One significant problem is that the operator of the boat must be careful to lift the daggerboard 28 before the boat is beached. In addition, daggerboard 28 causes additional resistance as the boat 30 travels through the water, thus losing some of the speed gained by employing symmetrical hulls.
From the discussion above, however, it is clear that prior art hull designs have included some compromises. While asymmetrical hulls are found to be slightly slower than symmetrical hulls, asymmetrical hulls are generally significantly more stable and may not require the use of daggerboards. Likewise, while symmetrical hulls are fast, they are unstable and usually require the use of daggerboards to maintain stable operations.
Another problem encountered in currently available catamarans is associated with transporting and storing the boat when not in use. Most conventional catamarans have cross bars which connect the two hulls and which provide support for the passenger area, generally comprising a "trampoline." Generally the cross bars are securely attached to the hulls of the boat so that the width of the boat remains constantly approximately 8 feet. Thus, special trailers and storage facilities are required to handle conventional catamarans.
Thus, what is needed in the art is a catamaran which is easily transported and stored. In addition, it would be an advancement in the art to provide a catamaran hull that is fast yet does no require the use of daggerboards for stability. It would be a further advancement in the art to provide a catamaran hull which has no more wetted surface than conventional symmetrical hulls. It would be a further advancement in the art if such a hull could be provided which was as stable as conventional asymmetrical hulls but was capable of operation without the use of daggerboards or other similar conventional means of stabilizing the hull. It would be another advancement in the art to provide a catamaran which is flexible in use being usable as a dinghy, a wind surfer, a fishing boat, and for other uses. Such a catamaran and catamaran hull are described and claimed below.